Every drawing application (regardless of the operating system), consists of three common components: a canvas, a brush or pen, and a process.
The canvas is the space on which objects will be drawn. For example, in a Windows application, a Windows Form is a canvas.
A brush or a pen represents the texture, color, and width of the objects to be drawn on the canvas.
The process describes how objects are drawn on the canvas.
To draw graphics objects you need to have a pen or a brush, which defines the texture, color, and width of the drawing. For example, if you draw a line or a rectangle, you need to create a pen with a color and width.
The process component of the drawing application includes making a call to draw the line or ...